ClinicalTrials.gov number

Protocol/serial number

Study information

Scientific title

Acronym

Study hypothesis

Elective lower limb arterial surgery is performed in patients with critical ischaemia due to atherosclerosis. These patients often have severe co-morbidity and are at high risk of post-operative complications. Maintaining optimal circulation is important during and after surgery in patients with general atherosclerotic disease.

Precise and individual circulatory therapy can be performed by continuously monitoring and optimising the patient's stroke volume and oxygen delivery during and after surgery. Optimisation is performed by giving colloid boluses to achieve the individual optimal stroke volume intra-operatively, supplemented by infusion of dobutamine post-operatively to maintain delivery of oxygen above 600 ml/min/m2.

This protocol may reduce post-operative complications and death, as well as length of stay in the hospital.

Primary study design

Secondary study design

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Patient information sheet

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Condition

Primary elective lower limb arterial surgery

Intervention

Patients were assigned to Individual Goal Directed Therapy (IGDT) or control groups by computer-generated random sequence.

The intervention period started pre-operatively, when monitoring with the Lithium Dilution Cardiac Output (LiDCO)-plus-system was established and calibrated at arrival to the operating theatre. The intervention period ended 6 hours post-operatively. Patients were followed for 30 days post-operatively.

Establishment and calibration of the LiDCO-plus-system were carried out by a member of the research team who had no involvement in the peri- and post-operative care and decision making. This allowed complete blinding of both surgical, anaesthetic and Post Anaesthetic Care Unit (PACU) clinical teams to LiDCO-plus-system readings in the control group.

All anaesthetic interventions were at the discretion of the anaesthetist responsible for the peri-operative management of the patient. All patients were fasting over night and no pre-operative intravenous fluids were given. Patients received general anaesthesia with fentanyl, thiopental, rocuronium and sevoflurane in oxygen/air or spinal anaesthesia with bupivacain 0.5% spinal solution. In all patients an epidural catheter was inserted at the L3-L4 level and an epidural infusion of bupivacain with fentanyl was initiated before start of surgery or after two hours, if spinal anaesthesia was used and continued until postoperative day 2 or 3.

Stroke volume index (SVI), cardiac index (CI) and oxygen delivery index (DO2I) were continuously monitored, by lithium indicator dilution and pulse power analysis using the LiDCO-plus-system in all patients, but data was blinded in the control group.

All patients were treated to achieve a heart rate less than 100 bpm or less than 20% above baseline, a mean arterial pressure (MAP) between 60 - 100 mgHg, a central venous pressure (CVP) between 4 - 16, body temperature greater than 36.5°C, an arterial oxygen saturation (SaO2) greater than 94%, a haemoglobin concentration greater than 6 mmol/l, and an urine output greater than 0.5 - 1.0 ml/min/kg in the post-operative period.

In all patients crystalloid, colloid, blood products and vasopressors were administered in the peri-and post-operative periods by the anaesthetist based on intra- and post-operative losses, standard haemodynamic parameters and blood-gases.

Intervention: Patients in the intervention group received 250 ml boluses of intravenous colloid solution (Voluven®, Fresenius Kabi AB, Upsala, Sweden) to achieve a sustained rise in SVI of at least 10% for 20 minutes in the peri- and post-operative period. Fluid boluses of Voluven® were repeated if SV subsequently decreased or if there was clinical suspicion of hypovolaemia. Furthermore, in the post-operative period, the IGDT group received dobutamine up to a maximum of 10 µg/kg/min if DO2I did not reach 600 ml/min/m2 with intravenous fluid alone. During infusion of dobutamine, monitoring was supplemented with 5-lead-electrocardiography, and at signs of myocardial ischaemia or heart rate greater than 100 minutes or greater than 20% above baseline, infusion was reduced or discontinued.